Geologic Background:
The steep-sided, glacier-clad Tolima volcano
contrasts with the broad profile of Ruiz volcano to the
north. The andesitic-dacitic younger Tolima volcano
formed during the past 40,000 years, rising above and
largely obscuring a 3-km-wide late-Pleistocene caldera.
The summit consists of a cluster of late-Pleistocene to
Holocene lava domes that were associated with thick
block-lava flows on the northern and eastern flanks and
extensive pyroclastic-flow deposits. The summit contains
a funnel-shaped crater 200-300 m deep. Holocene activity
has included explosive eruptions ranging in size from
moderate to plinian. The last major eruption took place
about 3600 years ago. Lava dome growth has produced
block-and-ash flows that traveled primarily to the NE and
SE.
Historic Activity:
- Minor explosive eruptions have been recorded from
Tolima in the 19th and 20th centuries.
- Last eruption in 1943.
Recent Activity:
Data Sources:
- Smithsonian's SEAN Bulletin (V. 13, No. 10).
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